Mapping Of QTL For Resistance Of Gray Leaf Spot In Maize

Gray leaf spot is a global corn disease,which poses a serious hazard to corn production and quality in various corn growing regions.GLS is quantitative trait controlled by micro-effect and multiple genes,exploring resistant gene has large difference on cultivating variety of resistance GLS.In this study,the double haploid（DH）population and immoral F₂（IF₂）population constructed by 08-641（susceptible disease of Cercospora Zeina）and 646（resistant disease of Cercospora Zeina）.The genetic linkage map of SNP markers was mapped,combined with phenotypic of multiple environment,mapped QTL of resistance GLS.The target plants were screened by BC₁F₁ population,which laid the foundation for fine mapping and molecular marker-assisted breeding.The main findings are as follows:1.Normal distribution test results showed that DH population and IF₂ population were normal distribution population.The results of variance analysis of gray leaf spot showed that there were significant differences among 86 DH lines and 226 IF₂ combination plants.2.According to the results of the Maize SNP50 Bead Chip SNP chip,screening polymorphism 163 SNP markers between 08-641 and 646,genotyping DH population.A genetic linkage map was constructed with 122 SNP markers at DH population,which covered 1501.19c M of the maize genome,average distance of 12.31c M.A genetic linkage map was constructed with 141 SNP markers at IF₂ population,which covered 1858.59c M of the maize genome,average distance of 13.18c M3.Using ICIMapping4.0 software and ICIM model performed QTL Mapping of resistance gray leaf spot.Five QTLs were located in DH population,respectively,q Rgls DH1-1,q Rgls DH1-2,q Rgls DH2-1,q Rgls DH4-1,q Rgls DH8-1.The contribution rate of explained phenotypic variation ranged from 6.69%-16.97%,q Rgls DH4-1 explained the largest phenotypic variation and LOD value.The additive effects were 0.8385,0.6523,0.9637,1.0398 and 1.1014.The resistance genes derived from the resistant parent 646.4.Using ICIMapping4.0 software and ICIM model performed QTL Mapping of resistance gray leaf spot.Using the genetic linkage map of DH population,six QTLs were mapped in IF₂ population,respectively,q Rgls IF1-1,q Rgls IF2-1,q Rgls IF2-2,q Rgls IF4-1,q Rgls IF9-1,q Rgls IF10-1.Account for phenotypic variation ranged from 1.52%-16.81%.Phenotypic variation and LOD value of q Rgls IF1-1 and q Rgls IF4-1were the largest.The additive effects were 1.6765,1.0698,1.234,1.5542,-0.8181 and-0.0295.Except for q Rgls IF9-1 and q Rgls IF10-1 were derived from the susceptible parent 08-641,the rest were derived from 646.5.Using ICIMapping4.0 software and ICIM model performed QTL Mapping of resistance gray leaf spot.Using the genetic linkage map of IF₂ population,seven QTLs were mapped in IF₂ population,respectively,q Rgls IF1-1,q Rgls IF2-1,q Rgls IF2-2,q Rgls IF4-1,q Rgls IF7-1,q Rgls IF9-1,q Rgls IF10-2.Account for phenotypic variation ranged from 1.89%-17.43%.Phenotypic variation and LOD value of q Rgls IF1-1 and q Rgls IF4-1were the largest.The additive effects were 1.4945,1.0437,1.1349,1.2403,0.7655,-0.6932 and 0.2868.Except for q Rgls IF9-1 were derived from the susceptible parent 08-641,the rest were derived from 646.The QTL on chromosome 1,2 and 4 were detected simultaneously in both populations,contribution rate more than 10%.6.KASP primers were developed based on the flank SNP markers of eight QTL,which screened BC₁F₁population.Combined with phenotypic,q Rgls1-2,q Rgls2-2,q Rgls4-1,respectively,obtained 7,4,9 interest plants.It was selected that one flanking markers are heterozygous,background recovery rate are higher,the phenotype is significantly better than susceptible.